Hubris, the ancient Greeks taught, is followed by Nemesis; overbearing presumption always finds the goddess of divine retribution and vengeance baying at its heels. Washington is learning that painful lesson again today -- and Iraqi civilians and American troops are paying the price for the pride that drove the United States to try to implant democracy on the cheap in the heart of the Arab world.

So who's to blame? It is fast becoming established wisdom that it was the Pentagon's political leaders -- especially Secretary of Defense Donald Rumsfeld, his neoconservative first-term deputy Paul Wolfowitz, and the cocksure chief of their policy shop, Douglas J. Feith -- who, above all, led us down the road to disaster in Iraq. But it's too neat to pin the culpability on the Defense Department's pinstripe-wearing civilian leaders and ignore the blunders of the uniformed top brass or, for that matter, the rest of the U.S. government; as they did in Vietnam, the nation's military and civilian leaderships share the responsibility for what's gone wrong. In his compelling and well-researched book, Thomas E. Ricks, a Pulitzer Prize-winning reporter for The Washington Post, painfully but clearly reveals an important truth about the Iraq debacle: It has a thousand fathers.

As the title implies, Fiasco pulls no punches. Sure enough, Rumsfeld, Wolfowitz and Feith come off badly in Ricks's account. But so do most Democratic members of Congress (whom Ricks labels not doves but "lambs" for their failure to oversee the executive branch) and the media, particularly the New York Times, which failed miserably to probe the Bush administration's war justifications and postwar planning. Ricks is also particularly scathing toward L. Paul Bremer, who led the civilian occupation authority in Iraq in 2003-04. Ricks quotes one colonel who described the efforts of Bremer's Coalition Provisional Authority as "pasting feathers together, hoping for a duck."

Troubling as these failures are, they are by now reasonably familiar; what's far less well-known is the bungling of the senior military leadership. With devastating detail, Ricks documents how U.S. generals misunderstood the problems they faced in Iraq and shows how poorly prepared the Army was for the unanticipated danger of a postwar Sunni rebellion. For ignoring the risks of an insurgency after Saddam Hussein's fall, Gen. Tommy Franks, the head of U.S. Central Command, "flunks strategy," Ricks writes; the war's commanding general designed "perhaps the worst war plan in American history." Gen. Richard Myers, the chairman of the Joint Chiefs of Staff during the invasion, and his deputy, Gen. Peter Pace (who's since been promoted to take Myers's old job), come off as smiling yes-men who went along with amateurish impulses from the Bush administration's political leadership and who forsook their duty to offer detached, professional judgments, acting instead as administration flacks in both private and public.

As a result of the lapses of the top brass and the haughtiness of Rumsfeld's men, the U.S. military came into Iraq inadequately prepared -- and hard-pressed to adapt. From the start, it failed to recognize that ensuring public order was the key to postwar success. As one general puts it, "I was on a street corner in Baghdad, smoking a cigar, watching some guys carry a sofa by -- and it never occurred to me that I was going to be the guy to go get that sofa back."

As the insurgency deepened, the Pentagon's military and civilian leaders first ignored it, then worsened it by using wrongheaded tactics. By emphasizing killing the enemy rather than winning over the people, the U.S. military made new enemies more quickly than it eliminated existing foes. Mass arrests and other attempts to intimidate Iraqis backfired, swelling the insurgents' ranks. U.S. units and troops deployed to Iraq turned over quickly, shuttling in and out of the country with little attempt to build a coherent intelligence picture of the situation on the ground or to sustain hard-won relationships with the local Iraqi officials trying to make their country work. Cities such as Mosul and Fallujah were liberated from insurgents and then abandoned; inevitably, the insurgents took over again. Such mistakes are depressing but not entirely surprising: The U.S. military has forgotten many of the lessons of counterinsurgency warfare that it learned bitterly in Vietnam and elsewhere. Having neglected counterinsurgency in the military's training and education programs, we should not be shocked that we are ill-equipped to wage it.

Indeed, the picture Ricks paints is so damning that it is, at times, too charitable to say that the military and civilian leadership failed. Fiasco portrays several commanders as misguided but trying their best, but others -- particularly the hapless Franks -- appear not to have tried at all. Worse, the overall war and occupation effort lacked the high-level White House coordination essential to victory, allowing Bremer to operate on his own, making major decisions without consulting the Pentagon or the National Security Council, let alone his counterparts on the military side of the occupation.

These failures feel particularly raw given the sacrifices, grit and determination of the heroes of Ricks's book: the junior and noncommissioned officers risking their lives in Iraq's streets, as well as the few innovative senior officers, such as Lt. Gen. David H. Petraeus, who have shrewdly tried (as the New Yorker's George Packer has put it) to win "over the civilian population by encouraging economic reconstruction and local government." Whether getting supply convoys past insurgent strongholds, identifying ways to defeat the rebels' dreaded IEDs (improvised explosive devices) or deciding whether to cow or charm local leaders, creative officers often invented new tactics and strategy on the spot. When they succeeded, they frequently did so in spite of their leaders. Interviews with such gallant soldiers, as well as their e-mails, blogs and private reports, form the core of Ricks's reporting.

And that reporting is impressive indeed. News on Iraq usually comes in blaring headlines, with little sense of trends and context, but Ricks's work allows us to fit seemingly disparate events into an overall pattern. Take the moral and political catastrophe of the abuse of prisoners at Abu Ghraib; Ricks shows the cruelty as not only a failure of command and discipline by the overmatched unit running the prison but also the result of obtuse higher-level decisions about how to fight the insurgents. Several army units, he reports, indiscriminately arrested Iraqis, making no attempt to separate the few who might know something about the insurgents from the many who were simply in the wrong place at the wrong time. The detention system as a whole was chronically understaffed and overwhelmed by the thousands of detainees pouring in, Ricks writes. That did not make the depravity of Abu Ghraib inevitable, but it did make accidents far more likely to happen.

Ambitious as it is, Fiasco does not offer a comprehensive picture of Bremer's occupation authority or the shadowy insurgency itself. It concentrates on the first year of the occupation, often addressing the subsequent two years of struggle largely as a contrast to the occupation's early days. Beyond this narrow focus, Ricks's penetrating book has perhaps only one other weakness: He is too optimistic about how much the Army has done to embrace a Petraeus-style, hearts-and-minds-based counterinsurgency doctrine today. Ricks is right to note positive U.S. moves such as revamping training programs and changing leadership, but the Army is still too focused on winning battles against individual insurgents and not focused enough on providing security for the Iraqi people as a whole, which is the key to undermining the insurgents.

But these limits do not detract from the value of this powerful book. Ricks begins Fiasco with the ancient strategist Sun Tzu's admonition about how to achieve victory: "Know your enemies, know yourself." Clearly, those who took us to war in 2003 knew neither. The question today is whether they can learn. ·

Daniel Byman is the director of the Center for Peace and Security Studies at Georgetown University and a nonresident senior fellow at the Saban Center for Middle East Policy at the Brookings Institution.